1. Technical Field
The present invention is directed toward photographic equipment and more particularly to a slide mount for holding a transparency for use with a projector.
2. Background Art
Slide mounts are well known in the art and generally involve one of several configurations. The most well known slide mount comprises two pieces of cardboard with a central aperture therein. The pieces of cardboard are bound together about their periphery by an adhesive. A transparency is secured intermediate the pieces of cardboard with its image in the central aperture. These mounts have several problems. First, they are subject to warping when exposed to moisture or humid conditions. Second, the transparency is tightly secured to the cardboard frames with no freedom of movement. As a result, when the transparency is exposed to heat, such as when viewed through a projector, the transparency expands causing it to warp or buckle in the central aperture, thereby distorting the projected image. In addition, the transparency may be removed only by cutting or tearing the mount, which not only destroys the mount, but exposes the transparency to potential damage.
A second group of slide mounts generally comprise two plastic or metal frame portions with a central aperture therein fastened together about their periphery by complimentary grooves and ridges. Alternatively, the frame portions are fastened by a tongue and groove configuration. These mounts also include two panes of glass secured by the frame covering the central aperture for containing a transparency between. These mounts also have several serious problems. First, the glass in the central aperture makes the mounts heavy. In addition, the glass may be broken during insertion of a transparency or if dropped in a dark room during a slide presentation, creating a potential hazard. Transparencies are also difficult to load into these mounts. Finally, because the mounts require glass panes and precisely fitting frame pieces, they are difficult and expensive to manufacture.
A third group of slide mounts generally comprises two plastic or metal frame portions with a central aperture therein which snap together or are slidably engaged about the periphery of the frame. As with the other prior art slide mounts, these slide mounts have major drawbacks. Because they must either snap or slide together, the frames must be precisely machined, increasing the cost and creating quality control problems in manufacture. Loading and aligning film within such frames is difficult and time consuming because the grooves and ridges which snap together or the tongue and grooves which slide together must be carefully aligned without misaligning the image on the transparency. Lastly, it may be difficult to separate the frames when changing transparencies.
Another group of slide mounts generally comprise two frame portions with central apertures therein joined at one edge by an integral hinge. The two frame portions are fastened together by cooperating groove and ridge structures. These mounts have the disadvantages of being difficult and expensive to manufacture and difficult to insert and remove transparencies from.
Yet another group of prior art slide mounts generally involve two frame portions with a central aperture therein defining inner edges of the mount. The frame portions are bound together about three of the four outer edges of the frame portions by an adhesive or by sonic welding. A film receiving cavity is formed between the frame pieces and comprises an elongated narrow passage extending from the unbound outer edge to the corresponding inner edge of the frame portions and grooves in the remaining inner edges of the frame portions. A transparency may be inserted into the frame by sliding it through the opening in the frame and into the grooves in the inside edges of the frame. Although an advancement over other prior art structures, such mounts have several problems. First, manufacture is expensive because the two frame pieces must be fastened together. In addition, inserting the bottom edge of a transparency in the slot in the inside bottom edge of such mount is difficult. Moreover, when the two frames are mounted together it has proven difficult to properly dimension the chamber. Thus, sometimes the cavity is too tight to receive a transparency and other times it is so loose that a transparency may fall out. A related problem is that these slide mounts are not adapted to receive transparencies of varying thicknesses. Thus, if the slots are configured to receive a thick transparency then thin transparencies can easily slide out of the mount. Conversely, if the slots are configured to receive a thin transparency, insertion of a thick transparency can be difficult or impossible.
One prior art structure, Netherlands Patent No. 162,399 to Geim, shows a slide mount with a spring activated closure. Specifically, Geim discloses a slide mount having two frame portions including a back frame portion and a front frame portion. The front frame portion is received within the back frame portion and attached thereto except along one side and a portion of the sides adjacent the one side which define an access panel to a transparency receiving cavity. The frame is made of a resilient material which normally biases the access panel in a closed position. A transparency may be inserted into the frame by pulling up on the access panel at the one side and forcing it into an open position and then sliding the transparency under the access panel. Upon releasing the access panel, it returns to the closed position substantially blocking access to the slide receiving cavity and trapping a transparency inserted therein. Geim has the advantage over much of the prior art in that it is able to accommodate transparencies of varying thicknesses. However, Geim has several serious problems. First, it can be difficult to pull up on the access panel so that a transparency may be inserted thereunder. Indeed, persons with limited dexterity may find it impossible. Second, Geim is a two piece construction which increases its cost. Third, because the access panel is at the slide receiving cavity inlet, if it is not pulled up enough during transparency insertion it will rub on and scratch the transparency, potentially ruining prized photographs.
The present invention is directed toward overcoming one or more of the problems discussed above.